<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<style>
    *{
        margin:0;
        padding:0;
    }
    #box{
        width: 1300px;
        height:800px;
        margin:50px auto;
        display: flex;


    }
    #box ul{
        width: 100%;
        height: 100%;
        flex-wrap: wrap;
        justify-content:center;
        align-items: center;
    }
    #box ul li{
        width: 50px;
        height: 50px;
        border:1px solid black;
        list-style: none;
        float: left;
    }
</style>

<body>

    <a href="www.baidu.com" title="baidu">aaaaaaa</a>
</body>

<script>

    let box = document.getElementById("box");
</script>
</html>